Simple integral, textbook seems wrong

  • Thread starter Thread starter Dumbledore
  • Start date Start date
  • Tags Tags
    Integral Textbook
Click For Summary
SUMMARY

The discussion centers on finding the equation of a curve with a slope defined by the function (ln x)^2/x, passing through the point P(1, 2). The user integrates (ln x)^2 and arrives at the expression (ln x)^3/6 + 2, while the textbook states the solution is (ln x)^3/3 + 2. The discrepancy arises from the integration process, specifically the application of the factor of 1/2 in the integration of ((ln x)^2) 2/x dx, which the user does not understand.

PREREQUISITES
  • Understanding of integral calculus
  • Familiarity with logarithmic functions
  • Knowledge of integration techniques, particularly integration by parts
  • Ability to solve for constants in integration problems
NEXT STEPS
  • Review integration by parts techniques in calculus
  • Study the properties of logarithmic functions in calculus
  • Practice solving differential equations involving logarithmic expressions
  • Learn about the Fundamental Theorem of Calculus and its applications
USEFUL FOR

Students studying calculus, particularly those focusing on integration techniques, as well as educators seeking to clarify common misconceptions in solving differential equations involving logarithmic functions.

Dumbledore
Messages
33
Reaction score
0

Homework Statement



Find the equation of the curve for which the slope is (ln x)^2/x and passes through P(1, 2)


Homework Equations





The Attempt at a Solution



Integrate (ln x)^2 = 1/2 Integral( ((ln x)^2) 2/x dx)

I get: 1/2 [((ln x)^3/3) + C]

Then solving for C, I get C=2

Then my final answer is (ln x)^3/6 + 2

The textbook says it is (ln x)^3/3 + 2.

I don't get it.
 
Physics news on Phys.org
How exactly did you make this integration: Integral( ((ln x)^2) 2/x dx)
you should get out \frac{2ln(x)^3}{3}
Why did you actually put this factor 2 in the integral and divide by 2 again, I don't get why this makes sense.
 
Well I got \int \frac{(ln x)^2}{x} dx = \frac{1}{3} (ln x)^3 + C. Don't see where you got that factor of 1/2 from. C = 2, so that's right.
 

Similar threads

  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 14 ·
Replies
14
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 5 ·
Replies
5
Views
1K
  • · Replies 11 ·
Replies
11
Views
1K
  • · Replies 4 ·
Replies
4
Views
1K
  • · Replies 54 ·
2
Replies
54
Views
15K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 3 ·
Replies
3
Views
2K
Replies
4
Views
2K